中文摘要：

通过对位错引起的超声非线性行为理论模型的研究,发现超声非线性系数的变化与疲劳损伤累积过程中位错密度的变化趋势相对应。基于上述理论,利用非线性超声对45#钢三点弯曲试件的微裂纹扩展进行了检测,实验发现位错密度的变化趋势与微裂纹扩展的3个阶段紧密相关。因此,利用非线性系数作为特征参数实现了对微裂纹扩展不同阶段的表征,从而实现了金属构件剩余寿命的预测,并且验证了超声非线性系数与位错密度成正比的位错理论。

英文摘要：

An investigation on the basis of theory model of ultrasound nonlinear behavior aroused by dislocation found that ultrasounic nonlinear coefficient corresponds with dislocation in the process of fatigue damage accumulation.Micro-crack propagation of 45# steel three-point bend specimen was tested by using nonlinear ultrasounic approach,and the result shows that the variation of dislocation density has close relation with the change of three stages of micro-crack propagation.Therefore,different stages of micro-crack propagation were characterized by using nonlinear coefficient as character parameter,thus the prediction of residual lifetime of metal component was realized,and dislocation theory that ultrasounic nonlinear coefficient is in direct proportion with dislocation density was validated.